1. Field of the Invention
The present invention relates to methods of: processing a continuous cross section in a local area of a sample surface of a semiconductor device, a new material or the like by using a focused ion beam (hereinafter referred to as an FIB); and observing the continuous cross section by using a scanning electron microscope (hereinafter referred to as an SEM) and the like. The present invention also relates to a charged particle beam apparatus used for the methods.
2. Description of the Related Art
In Kato and Otsuka [2003] THE TRC NEWS, No. 84, pp. 40-43, Toray Research Center, a dual beam apparatus is described in which both irradiation axes in an FIB system and an electron beam system cross at an acute angle, and in which an image of a single area can be displayed in the form of scanning images of the two beams, that is, an image taken by a scanning ion microscope (hereinafter referred to as an “SIM image”) and an SEM image. As can be expected from the case of the electron beam system, by processing and forming a cross section with the FIB (which is hereinafter referred to as “FIB cross-sectioning”), observation of the processed cross section using the SEM (the observation with the SEM is hereinafter referred to as “SEM observation”) can be performed without tilting a sample. By repeatedly performing the FIB cross-sectioning and the SEM observation, it is possible to accumulate sequentially cross-sectioned images in a depth direction of a processed surface. That is, three dimensional (hereinafter referred to as 3D) observation can be performed. In Japanese Patent No. 2852078, a technology is disclosed in which heights of a sample surface at a plurality of points are detected using a laser beam, and a tilt of the sample surface is calculated by using the information on heights at the plurality of points.
In the SEM observation in a depth direction of a processed cross section, by repeatedly performing the FIB cross-sectioning and the SEM observation, since the processed cross section moves in the depth direction, a deviation in an observation field of view and a deviation in focus occur in the SEM observation due to the movement of the processed cross section.